Attaining Full Li‐Ion Storage Capacity in Nearly Defect‐free and Preferential Orientation Grown LiCoPO4 Via ab initio Solvothermal Crystallization Control

Defect-free and preferentially grown LiCoPO₄ (LCP) crystals validated by first-principles calculations are engineered through solvothermal synthesis with ethylene glycol and Argon-annealing. The new LCP crystal type exhibits enhanced Li-ion intercalation dynamics and superior electrochemical near-theoretical Li-ion storage capacity opening the path towards realizing high-voltage cathode performance.

Abstract

Boosting energy density beyond the current status of Li-ion batteries is actively sought after yet it remains very challenging. One promising pathway toward this goal is the development of defect-free high-voltage cathode materials via novel crystal engineered approaches. In response to this demand, the present study focuses on synthesizing LiCoPO₄, which is a high-voltage polyanionic compound, into nearly defect-free structure and preferential orientation grown crystals via solvothermal method using ethylene glycol (EG) as surface energy control medium. Notably, ab initio molecular dynamics simulations and density functional theory calculations elucidate the role of interfacial energy variations induced by EG molecule interaction with particular crystal facets of LiCoPO₄ giving rise to the desired growth direction in comparison with hydrothermal method. In addition to solvent regulated crystal growth, Argon-annealing alleviates the undesired charge transfer resistance on the crystal surface by eliminating EG residue and further reduces the anti-site defect concentration, thereby engineering essentially highly ordered crystal structure. The novel LiCoPO₄ crystals are shown to possess nearly theoretical full discharge capacity (163.0 mAh g⁻¹ and 774.7 Wh kg⁻¹ at C/10) and superior rate capability (151.6 mAh g⁻¹ and 716.9 Wh kg⁻¹ at 1 C), a truly unmatched functionality offering new high-voltage cathode design possibilities.